Hypnotism in the base rules puts 2d4 HD into a trance., Sleep puts 4 HD asleep.
In DDO hypnotism has no such HD limitations, but sleep still does.
Deep slumber is 10 HD..

I suggest doubling the HD limitaion, that way the spells would become usable. Sleep would put 8HD asleep , deep slumber would put 20 HD asleep.

Remember they STILL get a will save in addition to the limitation.



Other HD or hitpoint limited spells would also benefit from a pump. The power word spells, circle of death, undead to death, cause fear, daze monster etc.